#include<bits/stdc++.h>
using namespace std;
struct value
{
	double m,v;
	bool operator < (const struct value & x)const
	{
		return x.v/x.m<v/m;
	}
}va[1000];

int main()
{
	int i,n;
	double t;
	cin>>n>>t;
	for(i=1;i<=n;i++)
		cin>>va[i].m>>va[i].v;
	sort(va+1,va+i);
	double total=0,sum=0;
	for(i=1;i<=n;i++)
	{
		if(total+va[i].m<=t)
		{
			total+=va[i].m;
			sum+=va[i].v;
		}
		else
		{
			sum+=(t-total)/va[i].m*va[i].v;
			total=t;
		}
	}
	printf("%.2f",sum);
    return 0;
}
